Method for forming a compact sensing apparatus in a dual-piece monolithic substrate

ABSTRACT

A sensing apparatus having a sensor formed in a monolithic semiconductor substrate and oriented orthogonally to a signal conditioner is provided. The sensor generates a sensing signal in response to a predetermined physical stimulus. A signal conditioner electrically connected and responsive to the sensor conditions the sensing signal. The sensor and signal conditioner are formed on wafer surfaces of a single semiconductor substrate cut from a semiconductor wafer. The substrate is separated, one portion having the sensor formed on therein and the other having formed therein the signal conditioner. The portions are oriented and rejoined to form a monolithic semiconductor substrate. The resulting monolithic substrate has, then, a sensor and signal conditioner formed therein and angled relative to each other at a predetermined angle.

RELATED APPLICATIONS

[0001] This application claims priority to Provisional ApplicationSerial No. 60/288,282, filed May 2, 2001, and incorporates by referencethe disclosures of Provisional Application Serial No. 60/288,312 filedMay 2, 2001, Provisional Application Serial No. 60/288,313 filed May 2,2001, Provisional Application Serial No. 60/287,856 filed May 1, 2001,Provisional Application Serial No. 60/287,763 filed May 1, 2001,Provisional Application Serial No. 60/288,281 filed May 2, 2001, andProvisional Application Serial No. 60/288,279 filed May 2, 2001.

FIELD OF THE INVENTION

[0002] The present invention relates to the field of sensing apparatusesand, more particularly, to the field of sensing apparatuses having asensing element formed in a monolithic semiconductor substrate.

BACKGROUND OF THE INVENTION

[0003] Many different types of electrical and mechanical systemsincorporate a sensing apparatus for detecting and measuring physical orchemical stimuli. Such sensing devices can be made to sense the presenceand intensity of electrical or magnetic fields. Similarly, sensingapparatuses can be made to detect mechanical forces, measuring thetemperature or flow of a liquid or gas, or register the acceleration ofa solid body.

[0004] Over the years various types of sensing devices have beendeveloped to accomplish these disparate tasks. The sensing apparatusesdeveloped rely on a transducer or other sensing element having aspecific preferred orientation in relation to the electrical or magneticfield or the a mechanical force to be sensed. Examples of electrical ormagnetic field sensing elements are position and proximity sensors suchas a Hall-effect cell, a magnetoresistor, a capacitive sensing element,and inductive sensing elements. An example of a mechanical force sensingelement is a stress gauge that measures mechanical stress or weight ofan object. Another example of a mechanical force sensing element is theaccelerometer, which measures the acceleration of an object.

[0005] These sensing devices, then, typically have a preferredorientation for the sensing element relative to the electrical ormagnetic field or to the physical force that is being sensed. The devicethus must be oriented so that the sensing element has the preferredorientation if the sensor's sensitivity is to be optimized. There alsomay be extraneous electrical or magnetic fields or mechanical forces inthe system with which the sensing device must accommodate, preferably byorienting the sensor relative to these extraneous fields or forces in aspecific direction so as to reduce the sensor's sensitivity to theextraneous fields or forces. Such orientation can reduce sensing errorsor noise caused by the movement of other objects or caused by thepresence of other fields or forces within the vicinity of the sensingdevice.

[0006] Sensing apparatuses typically also rely on signal conditioningcircuitry to amplify or otherwise condition the sensing signal thattypically has too low a magnitude to overcome extraneous noise effects.The signal conditioning circuitry is also employed to condition asensing signal that contains a large offset or other error signal thatcan overdrive sensitive monitoring equipment. Indeed, the signalconditioning circuitry can condition a sensing signal not otherwiseconducive to transmission over an extended distance to a remotelylocated electrical device such a sensor monitoring circuit.

[0007] Thus, regardless of the specific nature of the stimulus to besensed by a sensing apparatus, the device typically must include signalconditioning circuitry connected to a sensing element, which in turn, ispositioned in a preferred orientation so as to maximize its sensingsensitivity.

[0008] Prior art sensing apparatuses typically are manufactured with thesensing element and the signal conditioning circuitry on a common-planewafer, both which are interconnected via conductors (e.g., using metalor other conductive traces) formed on the same plane. These prior artdevices typically are then installed in an electrical or a mechanicalsystem with the sensing element oriented in a specific directionrelative to the field being sensed. For a sensing apparatus having thesensing element and signal conditioner formed on a common-plane, then,the orientation also determines the orientation of the signalconditioner.

[0009] The amount of area occupied by the sensing element is ordinarilymuch smaller than the area required for the signal conditioningcircuitry. Common-plane orientation of both the sensing element and thesignal conditioning circuitry, therefore, generally produces a sensingapparatus having a larger cross section than could otherwise be achievedwere the sensing element and the signal conditioner separately orientedin directions. This is an increasingly important consideration becausesensing apparatuses are employed in electrical and mechanical systemsthat are increasingly smaller and thus require evermore compact sensingdevices. In addition, the sensing apparatuses are increasingly taskedwith ever more complicated functions, necessitating accordingly morecomplex circuitry. There is thus a need to reduce the size of sensingapparatuses by, for example, separately orienting the sensing elementand the signal conditioning circuitry.

[0010] At the same time, though, the reduced size can not come at theexpense of the structural integrity of the sensing apparatus becausesensing devices typically are used in electrical and mechanical systemsthat are subject to harsh conditions such as extreme vibrations andaccelerations, extreme temperature variations, exposure to harshchemicals. Thus, while there is an ever greater need to reduce theoverall size of the sensing apparatus, there is a corresponding need tomaintain or enhance the structural integrity of the device.

SUMMARY OF THE INVENTION

[0011] With the foregoing in mind, the present invention advantageouslyprovides a sensing apparatus reduced in size by orienting of the sensorand signal conditioner in separate planes while maintaining the overallstructural integrity of the device. The sensor generates a sensingsignal in response to a predetermined physical stimulus. The signalconditioner senses the sensing signal generated by the sensor inresponse to the predetermined physical stimulus. The physical stimuluscan be an electric field, a magnetic field, or a mechanical force.

[0012] According to the method aspects of the present invention, thecompact sensing apparatus is formed by positioning a sensor on a wafersurface of a semiconductor substrate. Signal conditioning circuitrydefining a signal conditioner also is formed on a wafer surface of thesame semiconductor substrate. The substrate is separated and rejoined soas to form a monolithic semiconductor substrate. On the monolithicsubstrate, the sensor and signal conditioner are oriented relative toeach other at a predetermined angle. With the sensor and the signalconditioner so oriented, the overall size of the sensing apparatus isadvantageously reduced.

[0013] More specifically, the method comprises forming both a sensor andconditioning circuitry defining a signal conditioner on the singlemonolithic substrate. The substrate preferably is composed of asemiconductor material such as silicon or other semiconductor material.The monolithic substrate is formed by cutting it from a wafer thatitself has been sliced from an ingot composed of silicon or othersemiconductor material. If the monolithic substrate is cut from asemiconductor wafer, the wafer preferably is cut so as to provide amonolithic substrate having two opposing surfaces corresponding to theopposing surfaces of the wafer from which the monolithic substrate iscut. These opposing surfaces of the monolithic semiconductor substrate,then, define wafer surfaces of the substrate.

[0014] According to a first method, the sensor and the signalconditioner are formed on the same wafer surface of the monolithicsubstrate. A plurality of bonding pads and conductors for forming aconductive path between the sensor and the signal conditioner are alsoformed on the substrate. At least one conductor and bonding pad isformed on the wafer surface, while at least one conductor and bondingpad is formed on a cut plane oriented at predetermined angle relative tothe wafer surface of the substrate. Accordingly, the substrate on whichthe sensor and signal conditioner have been formed is separated. Thesensor and signal conditioner are then oriented relative to each otherat the predetermined angle and the corresponding conductors and bondingpads formed on the wafer surface and cut plane are aligned relative toeach other. In a final step, the aligned pieces on which the sensor andsignal conditioner are formed are rejoined to thereby form a compactsensing apparatus comprising a monolithic substrate having a sensor andsignal conditioner oriented at the predetermined angle.

[0015] Thus, the method comprises reorienting the sensor and the signalconditioner so that the sensor and the signal conditioner are positionedwith respect to each other at a predetermined angle on a monolithicsubstrate. The predetermined angle is defined by the angle of rotationbetween an imaginary initial plane extending substantially parallel tothe signal conditioner and an imaginary terminal place extendingsubstantially parallel to the sensor. The predetermined angle is greaterthan predetermined angle is greater than one hundred eighty (180)degrees. Preferably, the predetermined angle is two hundred seventy(270) degrees so that the sensor and the signal conditioner are orientedorthogonally relative to each other.

[0016] The sensor and signal conditioner can be formed on a common wafersurface of the monolithic substrate, or alternatively, on opposing wafersurfaces prior to separation of the substrate to form the two separatepieces. The method further comprises forming a path between the sensorand the signal conditioner with a plurality of bonding pads andelectrical conductors. Preferably, the conductive path will be formedafter the monolithic substrate on which the sensor and signalconditioner are formed has been separated into two pieces defining,respectively, the sensor and the signal conditioner, and having thesensor formed on the sensor substrate and the signal conditioner beingformed on the signal conditioner substrate.

[0017] In order to facilitate forming the conductive path between thesensor and the signal conditioner, at least one electrical conductor ispreferably formed on a cut plane of the sensor substrate for providingthe electrically conductive path between the sensor and the signalconditioner. Forming the electrical conductor on the cut plane permitsthe sensor to be positioned at any angle, including orthogonally,relative to the signal conditioner and the surface on which the signalconditioner is formed.

[0018] A further method aspect of the present invention provides forefficiently forming a plurality of compact sensing apparatuses. Aplurality of signal conditioners with bonding pads and conductors areformed on a single semiconductor wafer. The plurality of signalconditioners are formed spaced apart from one another and arrangedsubstantially in a row along the semiconductor wafer on which each isformed. A plurality of sensors also are formed. Each of the sensorsformed also are spaced apart and arranged in row-like fashion, eachcorresponding to one of the signal conditions formed on the samesemiconductor wafer. Multiple rows of sensors and corresponding signalconditioners can be formed on the same wafer, either on the same wafersurface or opposing wafer surfaces.

[0019] The semiconductor wafer is sliced into strips, each having arow-arranged set of sensors and corresponding signal conditioners. Thestrips are then arranged on edge and, on a cut plane of each strip, aplurality of bonding pads and conductors are formed. The bonding padsand conductors formed on the cut plane will be part of the conductivepaths that ultimately will be formed to electrically connect each sensorand corresponding signal conditioner. Each strip is then separated intoa plurality of single monolithic semiconductor substrates, each striphaving formed thereon on a sensor, signal conditioner, conductors, andbonding pads. Each monolithic substrate can then be formed into acompact sensing apparatus having a sensor and signal conditioner angledat a predetermined angle according to the methods described above.

[0020] Accordingly, each sensing apparatus formed according to themethod aspects of the present invention comprises a monolithic substratecreated by rejoining separate pieces of the same substrate. According toone method the monolithic substrate can be formed by rejoining theseparate pieces of the substrates, connecting them for example with athin film of nonconductive epoxy positioned between two surface portionsof the dual pieces.

[0021] The sensor and signal conditioner are electrically connected viaconductors that extend between the wire bond pads and the sensor and thesignal conditioner, respectively. More specifically, according toadditional method aspects of the present invention, recessed channelsare formed in the sensor substrate and subsequently filled with aconductive epoxy to form a conductive path between the sensor and thesignal conditioner. Specifically, at least one recessed channel isformed in the wafer surface of the signal conditioner substrate on whichthe signal conditioner is formed. The sensor substrate having the sensorformed also on a wafer surface is oriented so that at least one recessedchannel can be formed in a cut plane of the senor substrate.

[0022] The sensor substrate and the signal conditioner substrate arethen are oriented so that the at least one recessed channels on eachsubstrate align with one another. Electrical conductors extendingbetween the recessed channel on the sensor substrate and the sensor, aswell as between the recessed channel on the signal conditioner substrateand the signal conditioner can now be formed on the respectivesubstrates, or alternatively, are already formed thereon. Therefore,when the recessed channels are aligned, they can be filled with aconductive epoxy or other conductive thermosetting material therebycompleting a conductive path between the sensor and the signalconditioner.

[0023] It is important to note that the order in which the steps arecarried out can be varied. The recessed channels can be formed prior toseparation of the single monolithic substrate into a sensor substrateand signal conditioner substrate. Indeed, the recessed channels can beformed on the substrate prior to formation of the sensor and the signalconditioner. Alternatively, as described above, the recessed channelscan be formed after the single monolithic substrate is separated into asensor substrate and signal conditioner substrate but prior to joiningthe substrates to reform a monolithic substrate having the sensor andsignal conditioner oriented at a predetermined angle. As alluded toabove, the electrical conductors can be formed at various points in theprocess as well.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Some of the features, advantages, and benefits of the presentinvention having been stated, others will become apparent as thedescription proceeds when taken in conjunction with the accompanyingdrawings in which:

[0025]FIG. 1A is a perspective view of a sensing apparatus formed fromdual pieces of a semiconductor substrate according to the presentinvention;

[0026]FIG. 1B is a perspective view of a sensing apparatus formed fromdual pieces of a semiconductor substrate according to the presentinvention;

[0027]FIG. 1C is a perspective view of a sensing apparatus formed fromdual pieces of a semiconductor substrate according to the presentinvention;

[0028]FIG. 2A is a perspective view of a sensing apparatus formed fromdual pieces of a semiconductor substrate according to the presentinvention;

[0029]FIG. 2B is a perspective view of a sensing apparatus formed fromdual pieces of a semiconductor substrate according to the presentinvention;

[0030]FIG. 2C is a perspective view of a sensing apparatus formed fromdual pieces of a semiconductor substrate according to the presentinvention;

[0031]FIG. 3 is a side elevational view of a sensing apparatus accordingto the present invention;

[0032]FIG. 4 is a side elevational view of a sensing apparatus accordingto the present invention;

[0033]FIG. 5 is cross sectional view of the interface between a baseportion and encapsulation of the sensing apparatus according to thepresent invention;

[0034]FIG. 6 is a perspective view of a sensing apparatus according tothe present invention;

[0035]FIG. 7 is flow diagram of a method of forming a sensing apparatusaccording to the present invention;

[0036]FIG. 8 is flow diagram of a method of forming a sensing apparatusaccording to the present invention; and

[0037]FIG. 9 is flow diagram of a method of forming a sensing apparatusaccording to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0038] The present invention will now be described more fullyhereinafter with reference to the accompanying drawings which illustratepreferred embodiments of the invention. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout, the prime notation, ifused, indicates similar elements in alternative embodiments.

Sensing Apparatus Formed From Two Pieces of a Single MonolithicSubstrate

[0039] FIGS. 1A-1C illustrate a compact sensing apparatus 20 having asensor 22 and signal conditioner 24, the sensor 22 and the signalconditioner 24 being formed from the same monolithic semiconductorsubstrate 26 and angled relative to one another at a predeterminedangle, α. The predetermined angle, α, is defined as the angle ofrotation between an imaginary initial plane extending substantiallyparallel to the signal conditioner and an imaginary terminal planeextending substantially parallel to the sensor. The predetermined anglecan be any value greater than zero and up to three hundred sixty (360),but is preferably greater than one hundred (180) degrees. The sensor 22serves to generate a sensing signal in response to a predeterminedstimulus. The signal conditioner 24 is electrically connected to thesignal conditioner and conditions the signal generated by the sensor 22.The predetermined angle dictates the orientation of the sensor 22relative to the stimulus it is to sense, while also determining theoverall size of the sensing apparatus 20.

[0040] The single monolithic substrate 26 on which the sensor 22 and thesignal conditioner 24 are formed can, itself, be formed from asemiconductor wafer. As will be readily understood by those familiarwith the art, the semiconductor wafer will typically have been slicedfrom an ingot of semiconductor material. Each such slice of thesemiconductor ingot forms a circular wafer having two opposing wafersurfaces parallel to the planes through which the ingot has been slicedand an annular edge connecting the opposing surfaces thereby forming thesolid wafer.

[0041] According to the present invention, the monolithic substrate 26preferably will have been formed by through the opposing surfaces of asemiconductor wafer, the cutting being along preselected dimensionsdictated by the size of the sensor 22 and the signal conditioner 24which are to be formed on the resulting substrate. So formed, themonolithic substrate 26 has two surfaces (portions of the opposingsurfaces of the wafer from which the wafer has been cut), definingopposing wafer surfaces of the substrate. The sensor 22 and the signalconditioner 24 will be formed on a wafer surface of the monolithicsubstrate 26. According to the present invention, the sensor 22 andsignal conditioner 24 are formed either on the same wafer surface of thesubstrate or on opposing wafer surfaces of the same substrate.

[0042] As illustrated in FIGS. 1A-1C, in order to orient the sensor 22and the signal conditioner 24, the monolithic substrate is separatedalong the plane 21 between the portion of the substrate on which thesensor 22 is formed and the portion on which the signal conditioner 24is formed, both the sensor 22 and the signal conditioner having beenformed on the same wafer surface of the monolithic substrate 26. Thethen-separated portions of the substrate are oriented with respect toeach other at the predetermined angle and rejoined to thereby form amonolithic substrate having formed thereon a sensor 22 and signalconditioner 24 positioned relative to each other at substantially thepredetermined angle α.

[0043] Thus, in a first embodiment of the compact sensing apparatus, thesensor is formed on a first portion of a wafer surface of a singlemonolithic semiconductor substrate 20, and the signal conditioner 24 isformed on a second portion of the same wafer surface of the substrate20. The first and second portions of the wafer surface are then orientedwith respect to each other at the predetermined angle to therebysubstantially orient the sensor 22 and the signal conditioner 24relative to each other at the predetermined angle. FIGS. 1A-1Cillustrates the sensor 22 and the signal conditioner 24 being orientedorthogonally to each other. Other predetermined angles, however, arepossible and will be preferred if balancing the benefits of enhancedsensor 22 sensitivity (dictated by the sensor's orientation to thephysical stimulus to be sensed) and reduced sensing apparatus 20 size(determined by the orientation of the sensor 22 and the signalconditioner 24) dictates a preferred angle other than two hundredseventy (270) degrees.

[0044] FIGS. 2A-2C illustrate a second embodiment of a sensing apparatus40 in which the sensor 42 and the signal conditioner 44 are each formedon opposing wafer surfaces of the same monolithic semiconductorsubstrate. Specifically, the sensor 42 is formed on a portion of a wafersurface of a single monolithic semiconductor substrate and the signalconditioner 44 is formed on a portion of the opposing wafer surface ofthe same substrate. Then, again, the monolithic semiconductor substrateis separated and the wafer surfaces are oriented with respect to eachother to thereby substantially orient the sensor 42 and the signalconditioner 44 relative to each other at the predetermined angle. Aswith respect to the first embodiment, the predetermined angle can be anyangle and preferably is one that maximizes the overall efficiency of thesensing apparatus 40 by optimally balancing the benefit of angling thesensor 42 to achieve a specific sensing sensitivity against the benefitof angling the senor 22 relative to the signal conditioner 24 to limitthe overall size of the sensing apparatus 20.

[0045] FIGS. 1A-1C and 2A-2C also illustrate means for electricallyconnecting the sensor 22, 42 to the signal conditioner 24, 44 usingbonding pads 23, 25 and 43, 45. In the first embodiment of the presentinvention, a first plurality of bonding pads 23 is positioned on thewafer surface 27 of the monolithic substrate 26 and a second pluralityof bonding pads 25 is formed on an orthogonal, cut plane 29 of themonolithic substrate 26, the cut plane formed as a result of cutting thesubstrate 26 from a semiconductor wafer. As will be readily understoodby those familiar with the art, the bonding pads 23 formed on the wafersurface 27 will be electrically connected via conductors (e.g., metaltraces) to the signal conditioner 24.

[0046] Similarly, the bonding pads 25 formed on the cut plane 29 will beelectrically connected to the sensor 22. (Efficient methods for formingthe bonding pads and electrical conductors are described explicitly,below, in the context of the method aspects of the present invention.)As illustrated in FIGS. 1A-1C, the wafer surface 27 and the cut plane 29are oriented to face each other, and the wire bonds pads 23, 25 arealigned together to thereby provide a conductive path between the sensor22 and the signal conditioner 24. The corresponding bonding pads 23, 25preferably are connected by a conductive epoxy or other thermosettingmaterial.

[0047] FIGS. 2A-2C illustrate using a plurality of bonding pads 43, 45as part of the second embodiment of a compact sensing apparatus 40. Thesensor 42 is positioned on a sensor substrate, which as illustrated canbe formed by separating the monolithic substrate 46 on which the sensor42 is formed. The signal conditioner is positioned on a signalconditioner substrate, which also as illustrated, can be formed as aresult of the separation of the monolithic substrate 46 between thesensor 42 and the signal conditioner 44. As illustrated, a firstplurality of bonding pads 43 is formed on the wafer surface 47 of themonolithic semiconductor substrate 46. A recessed channel can be formedin the substrate 46 extending through the wafer surface 47 for forming asecond plurality of bonding pads 45 therein on a cut plane that willresult when the monolithic semiconductor substrate 46 is separated inorder to orient the sensor 42 and the signal conditioner 44, each formedon opposing wafer surfaces of the monolithic semiconductor substrate 46.(Again, efficient methods for forming the bonding pads and electricalconductors are described, below, in the context of the method aspects ofthe present invention.)

[0048] The sensor 42, also again, is oriented orthogonally to the signalconditioner 44. As illustrated in FIGS. 2A-2C, the cut plane on whichthe second plurality of bonding pads 45 is formed is parallel to thewafer surface 47 of the monolithic semiconductor substrate 46 so thatthe corresponding bonding pads 43, 45 lie in the same plane. The bondingpads 43, 45 preferably are connected with wire bonds as will beunderstood by those familiar with the art.

[0049] Thus, with respect to both the first and second embodiments, thecompact sensing apparatus 20, 40 preferably includes at least one cutplane on which is formed at least one bonding pad and at least oneelectrical conductor for forming a conductive path between the sensorand the signal conditioner to thereby electrically connect the sensorand the signal conditioner.

[0050] Both FIGS. 1A-1C and 2A-2C illustrate embodiments of the presentinvention in which the sensor 22, 42 and signal conditioner 24, 44 areformed on the same wafer surface or opposing wafer surfaces of the samemonolithic substrate, and then oriented with respect to each other. Moregenerally, a compact sensing apparatus according to the presentinvention comprises a monolithic substrate from which is formed a sensorsubstrate and a signal conditioner substrate, each having first andsecond surface portions and oriented at a preferred predetermined angle.Such a monolithic substrate having a sensor formed on the substrate andoriented orthogonally to a signal conditioner also formed on thesubstrate is illustrated in U.S. Pat. No. 5,670,886 to applicants andtitled Method and apparatus for Sensing Proximity or Position of anObject Using Near-Field Effects as well as in Applicant's co-pendingapplication titled Compact sensing Apparatus Having An Orthogonal Sensorand Methods For Forming Same, the disclosures of which are incorporatedherein in their entirety.

[0051] More generally, then, a sensor 22, 42 can be formed on a firstsurface portion of the sensor substrate, and a signal conditioner 24, 44formed on a second surface portion of the signal conditioner substrate.The first surface portions of the respective substrates are abuttinglyconnected to form a monolithic substrate having a sensor 22, 42 and asignal conditioner 42, 44 electrically connected to each other. Morespecifically, the first surface portion of the sensor substrateabuttingly connects to the first surface portion of the signalconditioner substrate such that the second surface portion of the sensorsubstrate and the second surface portion of the signal conditionersubstrate are oriented with respect to each other at a predeterminedangle greater than one hundred eighty (180) degrees. Preferably, thepredetermined angle is two hundred seventy (270) so as to therebyenhance compactness of the sensing apparatus. Again, the predeterminedangle is here defined as the angle of rotation between an imaginaryinitial plane extending substantially parallel to the second surfaceportion of the signal conditioner substrate and an imaginary terminalplane extending substantially parallel to the second surface portion ofthe sensor substrate.

Epoxy Bound Sensor and Signal Conditioner

[0052] As illustrated in FIGS. 1A-1C and described above, the sensor 22and the signal conditioner 24 are electrically connected via bondingpads 23, 25 fixedly connected with an epoxy or other conductivethermosetting material. More specifically, the bonding pads 23 cancomprise at least one recessed channel formed in a surface of asubstrate on which the signal conditioner 24 is formed, the substratedefining a signal conditioner substrate 33. Corresponding bonding pads25 can comprise at least one recessed channel formed on an orthogonalplane or other edge portion of the substrate on which the sensor 22 isformed, the substrate defining a sensor substrate 55. The bonding pads23, 24 can be aligned when the separate portions of the substrate arerejoined to form a monolithic substrate on which the sensor 22 andsignal conditioner 24 are formed and the epoxy or other thermosettingmaterial can be diffused into the corresponding at least one recessedchannel formed in the surface of the sensor substrate and into at theleast one recessed channel formed in the surface of the signalconditioner substrate to thereby form an adhesive layer mutually joiningthe respective substrates. The at least one channels of the sensorsubstrate and the signal conditioner substrate, being adequatelyaligned, thereby provide a common channel electrically bridging thesensor substrate 33 and the signal conditioner substrate 35 to therebyprovide a conductive path between the sensor 22 and the signalconditioner 24. In addition, the sensor substrate 35 and the signalconditioner substrate 33 can be abuttingly connected by mutual adhesion.The adhesion being effected, preferably, by a nonconductivethermosetting material positioned between the mutually abutting surfaceportions of the sensor substrate 35 and the signal conditioner substrate33 to thereby form an adhesive layer mutually joined to the respectivesubstrates.

Wire Bound Sensor and Signal Conditioner

[0053] As illustrated in FIGS. 2A-2C and described above, the sensor 42and the signal conditioner 44 can alternatively be electricallyconnected via wire bonds. More specifically, the bonding pads 43, 45 cancomprise wirebond pads. At least one wire bond pad 43 is positioned on asurface of the substrate on which the signal conditioner 44 is formed,the substrate defining a signal conditioner substrate 53. At least onewirebond pad 45 is positioned on an orthogonal plane or other edgeportion of the substrate on which the sensor 42 is formed, the substratedefining a sensor substrate 55. Each at least one bonding pad 43, 45 canbe aligned when the sensor substrate 55 and signal conditioner substrate53 are abuttingly joined to form a monolithic substrate on which thesensor 42 and signal conditioner 44 are formed. At least one wireconductor is then connected between the wirebond pads 43, 45 to therebyprovide a conductive path between the sensor 42 and the signalconditioner 44. In addition, the sensor substrate 55 and the signalconditioner substrate 53 are abuttingly connected by mutual adhesion,the adhesion preferably being effected by a nonconductive thermosettingmaterial positioned between the mutually abutting surface portions ofthe sensor substrate 55 and the signal conditioner substrate 55.

[0054]FIGS. 3 and 4 illustrate third and fourth embodiments of thepresent invention in which the compact sensing apparatus furthercomprises a base, an encapsulation, and an electrical conducting meansfor connecting the sensing apparatus to a preselected externalelectrical device such as a remote sensing monitor. In FIG. 3, a sensingapparatus 60 is mounted on a base 77. The base 77 supports a sensor 62and signal conditioner 64 formed, respectively, on a sensor substrate 75and a signal conditioner substrate 73. The substrates are abuttinglyjoined to form a monolithic substrate 66. The sensor 62 and the signalconditioner 64 are electrically connected by bonding pads positioned onthe sensor substrate 75 and the signal conditioner substrate 73, thebonding pads being connected by a conductive epoxy or otherthermosetting material as already described.

[0055] The sensing apparatus 60, moreover, is at least partially encasedby an encapsulation. As illustrated in FIG. 3, the encapsulation 79encapsulates the base 77 and the monolithic substrate 66 formed from thejoinder of the sensor substrate 75 and the signal conditioner substrate73 on which are formed, respectively, the sensor 62 and the signalconditioner 64. Conducting means extending outwardly through theencapsulation 79 connect the sensing apparatus 60 to the remoteelectrical device. Preferably, the conducting means comprises at leastone bonding pad 70 positioned on the signal conditioner substrate 73 andconnected to at least one conductor 71 to thereby provide a conductivepath between the signal conditioner 64 and the remote electrical device.

[0056]FIG. 4 illustrates a sensing apparatus 80 mounted on a base. Thebase 97 supports a sensor 82 and signal conditioner 84 formed,respectively, on a sensor substrate 95 and a signal conditionersubstrate 93, the substrates abuttingly joined to form a monolithicsubstrate 66. The sensor 82 and the signal conditioner 84 are connectedelectrically by wire bonds connected to a plurality of wirebond padsformed on each of the sensor substrate 95 and the signal conditionersubstrate 93. The sensing apparatus 80 is at least partially encased byan encapsulation 99. As illustrated in FIG. 4, the encapsulation 99encapsulates the base 97 and the monolithic substrate 86 formed from thejoinder of the sensor substrate 95 and the signal conditioner substrate93 on which are formed, respectively, the sensor 62 and the signalconditioner 64. The sensing apparatus 80 is connected to a remoteelectrical device by conducting means extending outwardly through theencapsulation 99. The conducting means preferably comprises at least onebonding pad 90 positioned on the signal conditioner substrate 93 andconnected to at least one conductor 91, providing therewith a conductivepath between the signal conditioner 84 and a sensing monitor or otherremote electrical device. An example of such conductor is a flexibleribbon cable encasing a plurality wire conductors.

[0057] Yet a further embodiment of a sensing apparatus 100 isillustrated in FIG. 5 in which the base 117 further comprises aroughened surface portion 118 which contacts a portion of theencapsulation 119 to increase friction at points of contact between thebase 117 and the encapsulation 119 to thereby reduce the probabilitythat the base 117 and the encapsulation 119 will separate from eachother when the sensing apparatus 100 is subject to unequal forces. Forexample, the roughened surface portion 118 of the base 117 contacting aportion of the encapsulation 119 can be an edge portion of the base 117that, as illustrated, is serrated Moreover, as illustrated in FIG. 6, ina sixth embodiment of a sensing apparatus 120, the sensing apparatus 120preferably comprises at least one recessed well 122 preferably formedwithin a bottom surface portion 123 of the base 137 to increase theextent of contact between the base 137 and the encapsulation 139 tothereby reduce the probability that the base 137 and the encapsulation139 will separate from each other.

Forming A Monolithic Sensing Apparatus From Two Pieces Of The SameSemiconductor Substrate

[0058] FIGS. 1A-1C and 2A-2C also illustrate the method aspects of thepresent invention for forming a monolithic sensing apparatus formed fromtwo pieces of the same monolithic semiconductor substrate. The methodcomprises forming both a sensor and conditioning circuitry defining asignal conditioner on the single monolithic substrate. The substratepreferably is composed of a semiconductor material such as silicon orother semiconductor material familiar to those skilled in the art. Themonolithic substrate is formed by cutting a semiconductor wafer beensliced from an ingot composed of silicon or other semiconductormaterial. If the monolithic substrate is cut from a semiconductor wafer,the wafer preferably is cut so as to provide a monolithic substratehaving two opposing surfaces corresponding to the opposing surfaces ofthe wafer from which the monolithic substrate is cut. These opposingsurfaces of the monolithic semiconductor substrate, then, define wafersurfaces of the substrate.

[0059]FIG. 7 more explicitly illustrates the method aspects of thepresent invention for forming a compact sensing apparatus. According toa first method 200, the sensor and the signal conditioner are formed onthe monolithic substrate (Block 201). More specifically, as illustratedin FIGS. 1A-1C, the sensor 22 and the signal conditioner 24 can beformed on the same wafer surface of the substrate 26. Alternatively, asperhaps best illustrated in FIGS. 2A-2C, the sensor 42 can be formed onan opposing wafer surface of the substrate 46 from the wafer surface 47on which the signal conditioner 44 is formed. As further illustrated inFIG. 7, the method 200 also includes forming a plurality of bonding padsand conductors for forming a conductive path electrically connecting thesensor and the signal conditioner (Block 202). At least one conductorand bonding pad is formed on the wafer surface, while at least oneconductor and bonding pad is formed on a cut plane formed orthogonallyor at another predetermined angle relative to the wafer surface of thesubstrate. According this first method 200, then, the substrate on whichthe sensor and signal conditioner have been formed is separated (Block203). The sensor and signal conditioner are then oriented relative toeach other at the predetermined angle and the corresponding conductorsand bonding pads formed on the wafer surface and cut plane are aligned(Block 204). In a final step of the method 200, the separate pieces onwhich the sensor and signal conditioner are formed are rejoined tothereby form a compact sensing apparatus comprising a monolithicsubstrate having a sensor and signal conditioner oriented at thepredetermined angle (Block 205).

[0060] Thus, the method 200 for forming the sensing apparatus furthercomprises reorienting the sensor and the signal conditioner so that thesensor and the signal conditioner are positioned with respect to eachother at a predetermined angle. If the predetermined angle is defined bythe angle of rotation between an imaginary initial plane extendingsubstantially parallel to the signal conditioner and an imaginaryterminal place extending substantially parallel to the sensor, then thepreferred predetermined angle is greater than predetermined angle isgreater than one hundred eighty (180) degrees. Preferably, thepredetermined angle is two hundred seventy (270) degrees so that thesensor and the signal conditioner.

[0061] According to method 200 illustrated by the steps shown in FIG. 7,in order to reorient the sensor and the signal conditioner to thepredetermined angle, the monolithic substrate on which the sensor andthe signal conditioner are formed is separated into two pieces, one onwhich the sensor is formed, defining a sensor substrate, and the otheron which the signal conditioner is formed, defining a signal conditionersubstrate. As described above and illustrated in FIGS. 1A-1C, the sensor22 and signal conditioner 24 can be formed on a common wafer surface ofthe monolithic substrate. Alternatively, as described above andillustrated in FIGS. 2A-2C, the sensor 42 and signal conditioner 44 canbe formed on opposing wafer surfaces prior to forming the two pieces.The method 200, as also described above, further comprises forming apath between the sensor and the signal conditioner with a plurality ofbonding pads and electrical conductors (Block 202). Preferably, theconductive path will be formed after the monolithic substrate on whichthe sensor and signal conditioner are formed has been separated into twopieces defining, respectively, the sensor and the signal conditioner,and having the sensor formed on the sensor substrate and the signalconditioner being formed on the signal conditioner substrate.

[0062] In order to facilitate forming the conductive path between thesensor and the signal conditioner, at least one electrical conductor ispreferably formed on a cut plane of the sensor substrate for providingthe electrically conductive path between the sensor and the signalconditioner. Forming the electrical conductor on the cut plane permitsthe sensor to be positioned at any angle, including orthogonally,relative to the signal conditioner and the surface on which the signalconditioner is formed.

[0063]FIG. 8 illustrates the method steps 300 for efficiently forming aplurality of compact sensing apparatuses. In this second method, aplurality of signal conditioners with bonding pads and conductors areformed on a single semiconductor wafer (Block 301). The plurality ofsignal conditioners are formed spaced apart from one another and arearranged substantially in a row along the semiconductor wafer on whicheach is formed. A plurality of sensors also are formed (Block 302),according to the method 300. Each of the sensors formed also are spacedapart and arrange in row-like fashion, each corresponding to one of thesignal conditions formed on the same semiconductor wafer. Multiple rowsof sensors and corresponding signal conditioners can be formed on thesame wafer according to the method 300.

[0064] The semiconductor wafer is sliced into strips, each having arow-arranged set of sensors and corresponding signal conditioners (Block303). The strips are then arranged on edge and, on a cut plane of eachstrip, a plurality of bonding pads and conductors are formed (Block304). The bonding pads and conductors formed on the cut plane will bepart of the conductive paths that ultimately will be formed toelectrically connect each sensor and corresponding signal conditioner asearlier described. Each strip is then separated into a plurality ofsingle monolithic semiconductor substrates, each strip having formedthereon on a sensor, signal conditioner, conductors, and bonding pads(Block 305). Each monolithic substrate can then be formed into a compactsensing apparatus having a sensor and signal conditioner angled at apredetermined angle according to the methods described above.

Bonding Methods Using A Thermosetting Material

[0065] FIGS. 1A-6, as described in detail above, illustrate methodaspects of the present invention for forming a compact sensing apparatusin which a sensor and corresponding signal conditioner are formed on asingle monolithic semiconductor substrate and angled relative to eachother at a predetermined angle. As described, the method essentiallyentails forming the sensor and signal conditioner on the substrate andthen separating the substrate such that the is formed on a sensorsubstrate and the corresponding signal conditioner is formed on a signalconditioner substrate. The sensor substrate and the signal conditionersubstrate are oriented to position the sensor and the signal conditionerrelative to each other at the predetermined angle. A monolithicsubstrate can then be reformed by structurally connecting thesubstrates. The sensor and signal conditioner are electrically connectedvia a conductive epoxy or similar thermosetting material.

[0066] A third method embodiment of the present invention foraccomplishing this result, again, entails forming the sensor and signalconditioner on the same wafer surface of a substrate, as illustrated inFIGS. 1A-1C and 2A-2C. The single substrate is separated so as to from asensor substrate and a signal conditioner substrate with the sensorformed on the sensor substrate and the signal conditioner formed on thesignal conditioner substrate. Recessed channels are formed in the sensorsubstrate and the signal conditioner, which subsequently can be filledwith a conductive epoxy to form a conductive path between the sensor andthe signal conditioner. Specifically, at least one recessed channel isformed in the wafer surface of the signal conditioner substrate on whichthe signal conditioner is formed. The sensor substrate having the sensorformed also on a wafer surface is oriented so that at least one recessedchannel can be formed in a cut plane of the senor substrate.

[0067] The sensor substrate and the signal conditioner substrate arethen are oriented so that the at least one recessed channels on eachsubstrate align with one another. Electrical conductors extendingbetween the recessed channel on the sensor substrate and the sensor, aswell as between the recessed channel on the signal conditioner substrateand the signal conditioner can now be formed on the respectivesubstrates, or alternatively, are already formed thereon. Therefore,when the recessed channels are aligned, they can be filled with aconductive epoxy or other conductive thermosetting material therebycompleting a conductive path between the sensor and the signalconditioner.

[0068] It is important to note that the order in which the steps arecarried out can be varied. The recessed channels can be formed prior toseparation of the single monolithic substrate into a sensor substrateand signal conditioner substrate. Indeed, the recessed channels can beformed on the substrate prior to formation of the sensor and the signalconditioner. Alternatively, as described above, the recessed channelscan be formed after the single monolithic substrate is separated into asensor substrate and signal conditioner substrate but prior to joiningthe substrates to reform a monolithic substrate having the sensor andsignal conditioner oriented at a predetermined angle. As alluded toabove, the electrical conductors can be formed at various points in theprocess as well.

[0069] In the drawings and specification, there have been disclosed atypical preferred embodiment of the invention, and although specificterms are employed, the terms are used in a descriptive sense only andnot for purposes of limitation. The invention has been described inconsiderable detail with specific reference to these illustratedembodiments. It will be apparent, however, that various modificationsand changes can be made within the spirit and scope of the invention asdescribed in the foregoing specification and as defined in the appendedclaims.

That claimed is:
 1. A method for forming a compact sensing apparatus,the method comprising: forming a sensor and a signal conditioner on amonolithic semiconductor substrate; and orienting the sensor and thesignal conditioner so that the sensor and the signal conditioner arepositioned with respect to each other at a predetermined angle greaterthan one hundred eighty (180) degrees, the predetermined angle beingdefined by the angle of rotation between an imaginary initial planeextending substantially parallel to the signal conditioner and animaginary terminal place extending substantially parallel to the sensor.2. A method for forming a compact sensing apparatus as defined in claim1, wherein the monolithic semiconductor substrate is formed from asemiconductor wafer and comprises two opposing wafer surfaces, andwherein the step of forming a sensor and a signal conditioner on themonolithic semiconductor substrate comprises forming the sensor and thesignal conditioner on the same wafer surface of the monolithicsemiconductor substrate.
 3. A method for forming a compact sensingapparatus as defined in claim 1, wherein the monolithic semiconductorsubstrate is formed from a semiconductor wafer and comprises twoopposing wafer surfaces, and wherein the step of forming a sensor and asignal conditioner on the monolithic semiconductor substrate comprisesforming the sensor and the signal conditioner on opposing wafer surfacesof the monolithic semiconductor substrate.
 4. A method for forming acompact sensing apparatus as defined in claim 1, the method furthercomprising forming at least one electrically conductive path between thesensor and the signal conditioner.
 5. A method for forming a compactsensing apparatus, the method comprising: forming a sensor and a signalconditioner on a single monolithic semiconductor, the monolithicsubstrate formed from a semiconductor wafer and having first and secondopposing wafer surfaces; orienting the sensor and the signal conditionerso that the sensor and the signal conditioner are positioned withrespect to each other at a predetermined angle greater than one hundredeighty (180) degrees, the predetermined angle being defined by the angleof rotation between an imaginary initial plane extending substantiallyparallel to the signal conditioner and an imaginary terminal placeextending substantially parallel to the sensor; and forming anelectrically conductive path between the sensor and the signalconditioner.
 6. A method for forming a compact sensing apparatus asdefined in claim 5, wherein the step of forming the sensor and thesignal conditioner on a single monolithic semiconductor comprisesforming the sensor on a first portion of a wafer surface of themonolithic substrate and forming the signal conditioner on a secondportion of a wafer surface of the same monolithic substrate.
 7. A methodof forming a compact sensing apparatus as defined in claim 6, the stepof orienting the sensor and the signal conditioner so that the sensorand the signal conditioner are positioned with respect to each other atthe predetermined angle comprises separating the monolithic substrateinto a sensor substrate and a signal conditioner substrate, the sensorsubstrate having the sensor formed thereon and the signal conditionersubstrate having the signal conditioner formed thereon, and positioningthe sensor substrate and signal substrate relative to each other tothereby orient the sensor at the predetermined angle relative to thesignal conditioner.
 8. A method for forming a compact sensing apparatusas defined in claim 8, wherein the method further comprises forming atleast one bond pad on the sensor substrate, the bond pad beingelectrically connected to the sensor formed on the sensor substrate, andforming at least one bond pad on the signal conditioner substrate, thebond pad being electrically connected to the signal conditioner formedon the signal conditioner substrate.
 9. A method as defined in claim 8,wherein step of forming an electrically conductive path between thesensor and the signal conditioner comprises electrically connecting atleast one conductor between the sensor and the signal conditioner, theat least one conductor having a first end connected to an at least onebond pad formed on the sensor substrate and a second end portionconnected to an at least one bond pad formed on the signal conditionersubstrate.
 10. A method as defined in claim 9, wherein the step offorming an electrically conductive path further comprises forming atleast one bond pad and positioning at least one conductor on a cut planeof the sensor substrate to thereby form at least a portion of theelectrically conductive path between the sensor formed on a wafersurface of the sensor substrate and the signal conditioner formed on awafer surface of the signal conditioner substrate.
 11. A method forforming a compact sensing apparatus, the method comprising: forming asensor and a signal conditioner on a single monolithic semiconductorsubstrate; separating the semiconductor substrate into a sensorsubstrate the sensor formed thereon and a signal conditioner substratehaving the signal conditioner formed thereon; fixedly positioning thesensor substrate and the signal conditioner substrate relative to eachother so that the sensor and the signal conditioner are oriented withrespect to each other at a predetermined angle greater than one hundredeighty (180) degrees, the predetermined angle being defined by the angleof rotation between an imaginary initial plane extending substantiallyparallel to the signal conditioner and an imaginary terminal placeextending substantially parallel to the sensor; and forming anelectrically conductive path between the sensor and the signalconditioner.
 12. A method for forming a compact sensing apparatus asdefined in claim 11, the method further comprising forming at least onerecessed channel in the sensor substrate and forming at least onerecessed channel in the signal conditioner substrate, the at least onerecessed channels being positioned to align with each other when thesensor substrate and the signal conditioner substrate are positionedrelative to each other so that the sensor and the signal conditioner areoriented with respect to each other at the predetermined angle, thealigned recessed channels providing a connected path between the sensorsubstrate and the signal conditioner substrate within which can bediffused a conductive thermosetting material to form the electricallyconductive path between the sensor and the signal conditioner.
 13. Amethod for forming a compact sensing apparatus as defined in claim 12,wherein the at least one recessed channel formed in the sensor substrateand the at least one recessed channel formed in the signal conditionersubstrate are both formed by forming a corresponding single recessedchannel in the single monolithic substrate prior to the separation ofthe single monolithic substrate, the single monolithic substrate beingseparated along a cut path that intersects single recessed channel suchthat after separation of the single monolithic substrate a portion ofthe single recessed channel forms the recessed channel formed in thesensor substrate and another portion of the single recessed channelforms the recessed channel formed in the signal conditioner substrate tothereby permit the channels to be aligned to from the connected pathbetween the sensor substrate and the signal conditioner substrate.
 14. Amethod for forming a compact sensing apparatus, the method comprising:forming a sensor and a signal conditioner on a single monolithicsemiconductor substrate; separating the semiconductor substrate into asensor substrate the sensor formed thereon and a signal conditionersubstrate having the signal conditioner formed thereon; flexiblypositioning the sensor substrate and the signal conditioner substraterelative to each other so that the sensor and the signal conditioner areoriented with respect to each other at a predetermined angle greaterthan one hundred eighty (180) degrees, the predetermined angle beingdefined by the angle of rotation between an imaginary initial planeextending substantially parallel to the signal conditioner and animaginary terminal place extending substantially parallel to the sensor;and forming an electrically conductive path between the sensor and thesignal conditioner.
 15. A method for forming a compact sensing apparatusas defined in claim 14, wherein the step of flexibly positioning thesensor substrate and the signal conditioner substrate comprisespositioning the sensor substrate and the signal conditioner substrate ona mounting base having sufficient pliability to permit the sensor andthe signal conditioner to shift positions relative to each other withina predetermined range of movements.
 15. A method for forming a compactsensing apparatus as defined in claim 14, wherein the mounting base is aflexible ribbon cable.
 16. A method for forming a compact sensingapparatus as defined in claim 13, further comprising etching the surfaceof the semiconductor substrate prior to separating the semiconductorsubstrate, the step of etching forming an etched portion of thesubstrate that is angled relative to the remaining surface portion ofthe substrate.
 17. A method for forming a compact sensing apparatus asdefined in claim 16, further comprising metallizating at least a portionof the monolithic substrate including the etched portion of thesubstrate to form wire bond pads along the etched portion of thesubstrate.
 18. A method for forming a compact sensing apparatus, themethod comprising: forming a sensor and a signal conditioner on amonolithic semiconductor substrate; separating the semiconductorsubstrate into a sensor substrate on which the sensor is formed and asignal conditioner substrate on which the signal conditioner is formed;positioning the sensor substrate and the signal conditioner substrate ona flexible conducting cable; bending the flexible conducting cable sothat the sensor and the signal conditioner are oriented with respect toeach other at a predetermined angle greater than one hundred eighty(180) degrees, the predetermined angle being defined by the angle ofrotation between an imaginary initial plane extending substantiallyparallel to the signal conditioner and an imaginary terminal placeextending substantially parallel to the sensor; and forming anelectrically conductive path positioned between the sensor and thesignal conditioner, the path being connected to the sensor and thesignal conditioner to electrically connect the sensor and the signalconditioner.
 19. A method for forming a compact sensing apparatus asdefined in claim 18, wherein the step of positioning the sensorsubstrate and the signal conditioner substrate on the flexibleconducting cable comprises fixedly joining the sensor substrate and thesignal conditioner substrate to the cable with an electricallyconductive thermosetting material.